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| select if | keeps selected cases in the data current data file |
| descriptives | procedure for obtaining means, standard deviations, etc. |
| save outfile | saves the current data file with a new name |
| display | displays requested file information |
| frequencies | calculates frequencies |
| add files | appends (stacks) data files (adds cases) |
| sort cases | sorts cases in the data file |
| match files | merges data files (adds variables) |
In this unit we will illustrate methods for subsetting data (in other words, using only some of the cases), appending data (adding cases from another SPSS data file), and merging data (adding variables from another SPSS data file).
Let's open the data file.
File Open Data choose c:\spss_data\hs1.sav
Let's pretend that we are working on our honors thesis and that we want to study just "good readers", those with reading scores 60 or higher. We will open the file and then "select cases" to include the students with reading scores of 60 or higher.
Data
Select Cases
click if "condition is satisfied" and click "if" box
read >= 60
Continue
choose "Delete unselected cases"
Notice that the undesired cases have now been deleted. Now we will save our data.
File Save as c:\spss_data\honors\hsgoodread.sav
Let's open the hs1 data file again.
File Open Data choose c:\spss_data\hs1.sav
We want to keep just some variables, including id female read and write. We keep these variables in the same procedure that we use to save the data file. Notice you can also choose keep all if that is more helpful to you.
File
Save as
choose c:\spss_data\hskept.sav
variables
drop all
click check boxes next to id, female, read, write
Save
File Display Data File Information Working File
Let's suppose we are working on our masters thesis. There are two files, one for the males (hsmale.sav) and one for the females (hsfemale.sav). We would like to combine these files. We will start by opening the file with the data for the males.
File Open Data c:\spss_data\hsmale.sav
As we can see, the variable female (which indicates gender) is a constant. This is what we would expect in a file with data only for males.
Analyze Descriptive Statistics Frequencies select female
Now we can append the files.
Data
Merge Files
Add Cases
An external SPSS Statistics data file
choose c:\spss_data\hsfemale.sav
Continue
We will now save the data file with a new name.
File Save As c:\spss_data\hsmasters.sav
Now let's suppose that we are working on our dissertation. The data are in two files, one with the demographic information (hsdem.sav) and one with the test scores (hstest.sav). We would like to match merge these files based on id. Before we can match merge these files, we need to open each file, sort it on id, and then save the sorted file.
File Open Data c:\spss_data\hsdem.sav
Data Sort Cases choose id
File Save As c:\spss_data\hsdem.sav
Now that we have sorted and saved the first file (hsdem.sav), we will do the same thing for the second file (hstest.sav).
File Open Data c:\spss_data\hstest.sav
Data Sort Cases choose id
File Save As c:\spss_data\hstest.sav
Finally, we will open the first file (hsdem.sav) and merge it with the second file (hstest.sav). We will save the merged data file with the name hsdiss.sav.
File Open Data c:\spss_data\hsdem.sav
It is important that we merge the data sets by the same variable on which we sorted the two files.
Data
Merge Files
Add Variables
An external SPSS Statistics data file
choose c:\spss_data\hstest.sav
Continue
click "match cases on key variable"
move id as key variable
click "Indicate case as source variable"
(name it fromtest)
Finally, we will save the data file with a new name.
File Save As c:\spss_data\hsdiss.sav
* working on honors thesis. * want to make a subset just keeping those who have read >= 60. get file "c:\spss_data\hs1.sav". * keeping cases for which students have a reading score of 60 or higher. select if read >=60. descriptives /var=read. save outfile "c:\spss_data\hsgoodread.sav". * pretend we have 2000 variables and we want to keep just some of the variables. * we want to keep just the variables id female read write. save outfile = "c:\spss_data\hskept.sav" /keep=id female read write. display names. get file "c:\spss_data\hskept.sav". display names. * extra example not in point and click. * we want to drop just the variables ses and prog. get file "c:\spss_data\hsgoodread.sav". save outfile "c:\spss_data\hsdropped.sav" /drop=ses prog. display names. get file "c:\spss_data\hsdropped.sav". display names. * have one file with males, females in another file and need to "append" the files. get file "c:\spss_data\hsmale.sav". freq /var=female. add files /file=* /file="c:\spss_data\hsfemale.sav". freq /var=female. save outfile "c:\spss_data\hsmasters.sav". * one file has demographic scores, the other has test scores and we want to "match merge" the files. get file "c:\spss_data\hsdem.sav". list cases from 1 to 10. sort cases by id. save outfile "c:\spss_data\hsdem.sav". get file "c:\spss_data\hstest.sav". list cases from 1 to 10. sort cases by id. save outfile "c:\spss_data\hstest.sav". get file "c:\spss_data\hsdem.sav". match files /file=* /in=fromdem /file="c:\spss_data\hstest.sav" /in=fromtest /by id. list cases from 1 to 10. list variables id fromdem fromtest. crosstab /tables=fromdem by fromtest. save outfile "c:\spss_data\hsdiss.sav".
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